Maintenance, upgrading and replacement of ageing utilities pipeline infrastructures are major issues facing utilities companies such as water and gas utilities companies. Pipeline networks typically include main supply pipelines (also referred to as the “mains” supply) and consumer service connection pipelines. (A “pipeline” or “pipe” may alternatively be termed simply a “conduit”, and as used herein such terms may be used interchangeably.) The consumer service connection pipelines are connected to the main supply pipelines typically by means of a T-connection, to deliver a supply of fluid such as water or gas to a consumer's premises from the main supply pipeline via the consumer service connection pipeline.
Utilities supply pipelines and the connections between main and consumer service connection pipelines are typically located underground, presenting substantial access problems and cost implications when maintenance, upgrading or replacement is required.
Ageing pipelines, of both main and consumer connection types, are also vulnerable to failure and leakage of fluid from pipelines is a known hazard, which can be particularly serious in the case of gas leakage.
One solution to reducing the cost of replacement of pipelines, both of mains and consumer service connection kinds, is to install replacement pipeline within pre-existing pipeline, leaving the pre-existing main and/or pre-existing consumer service connection pipeline in place. The replacement main pipeline has an external diameter that is smaller than the internal diameter of the pre-existing main pipeline, allowing it to fit within the pre-existing main pipeline infrastructure. Similarly, the replacement consumer service connection pipeline has a diameter that is smaller than the pre-existing consumer service connection pipeline. The replacement main pipeline may be referred to as a “main pipeline liner” or “mains liner” because it effectively lines the pre-existing main pipeline. Similarly, the replacement consumer service connection pipeline may be referred to as a “service connection liner” since it effectively lines the pre-existing consumer service connection pipeline. The consumer service connection pipeline may for example be of the Serviflex® type, this being a twin-walled corrugated flexible polyethylene liner pipe supplied by Radius Systems Ltd, of South Normanton, Alfreton, Derbyshire, UK.
In known methods of replacement main pipeline installation, the replacement pipeline is installed within the pre-existing pipeline by pulling the replacement pipeline through the pre-existing pipeline. Connection of the consumer service connection pipeline (or even a replacement liner inserted therein to repair same) into the replacement main pipeline is made by excavating ground above the location at which the pre-existing service connection pipeline connects to the pre-existing main pipeline. Installation personnel then remove a portion of the pre-existing main pipeline and pre-existing service connection pipeline in order to expose the replacement pipelines that have been installed therein. A T-connector is then installed on the replacement main pipeline and the replacement service connection pipeline coupled to the replacement main pipeline via the T-connector. The T-connector is typically attached to the main pipeline by forming an electrofusion bond between the T-connector and the main pipeline in a known manner.
Connections into the new main pipeline of existing or replacement side (or branch) connection pipelines of other types, apart from those to consumers' properties, may be made in the same manner.
In methods of installing a replacement pipeline within a pre-existing pipeline, especially a main pipeline, it is frequently necessary to utilise an apparatus, often a remote-controlled apparatus such as a “pig” or “robot”, that is insertable into and propellable along the main pipeline in order to carry out one or more operations on an inner wall thereof. Such operations may include for instance a cutting operation, e.g. a drilling operation for the purpose of forming a hole or aperture through the main pipeline wall in order to make a necessary service connection thereto, or an insertion operation, e.g. for inserting a connector device (such as the above-mentioned T-connector) or other fitting into the aperture thus formed, or a welding operation, e.g. to form a fluid-tight bond and seal between such newly installed components for completing the overall new service connection to the replacement main pipeline.
Such “pigs” or “robots” are often designed to be as small and lightweight as possible, and to that end it is common practice to provide such apparatuses with a multi-strand or multi-tube tether or umbilical cable via which it is linked to an above-ground control station and sources of electrical power, operational control signals, supplies of pressurised fluid to onboard pneumatic and/or hydraulic systems, and suchlike and provided. Such pigs or robots may also comprise several different sections or modules, e.g. each being constructed, designed and controlled to perform a given unique operation in the overall pipeline replacement procedure.
In practice however it is difficult to design such pigs or robots which are able to carry out particular dedicated tasks with efficiency and accuracy, in particular for example in terms of being controllable so as to be able to insert T-connectors or other fittings in pre-drilled apertures in an inner pipeline wall at the required locations and with stability and precision, and so as to form secure and efficient joints for completing the overall new service connection to the replacement main pipeline. Indeed, known attempts at providing such apparatus have hitherto failed to successfully address such shortcomings.
It is an aim of the present invention to address disadvantages associated with the prior art such as those discussed above.